fix missing method error

app/models/client.rb

@@ -70,7 +70,7 @@ class Client < ApplicationRecord
   }
 
   def terminatable?
-    assignment.blank? || assignment.ended? || assignment.no_period?
+    assignment.blank? || assignment.no_period? || assignment.ended?
   end
 
   def self.acceptences_restricted

app/models/concerns/group_assignment_and_assignment_common.rb

@@ -116,5 +116,9 @@ module GroupAssignmentAndAssignmentCommon
     def ending?
       period_start.present? && period_end.present?
     end
+
+    def no_period?
+      period_start.blank? && period_end.blank?
+    end
   end
 end